More than 5 inches of rain has fallen — 2 inches in one hour in some locations. Weather Underground recorded 1 inch in less than 15 minutes.

Rescuers took helicopters to collect residents from rooftops, including one dramatic effort to save two women from a home in Maricopa County, broadcast live by NBC News.

Thirteen miles of Interstate 17 had to close owing to the torrent. A north Phoenix high school had to relocate 12 classrooms when they started flooding, The Associated Press reported.

At one Phoenix intersection, 16 people in 10 cars had to be rescued when rushing water surged over the pavement. One video captured by ABC 15 shows a man on the roof of his inundated car as a firetruck approaches. He leaps to the truck just as the water starts to tip the car.

Some jaw-dropping statistics from Weather.com:

"Parts of northern Maricopa County had already topped 4 inches of rain as of late Tuesday morning. Rock Springs, officially a part of Black Canyon City, reported 5.56 inches of rain.

"Rain fell at the rate of 1.38 inches in 35 minutes near Beardsley on the city's far northwest side, and 1.75 inches of rain fell in just 45 minutes in the north suburb of Peoria.

"These amounts are greater than the average rainfall for the entire month of August at Phoenix Sky Harbor Airport (1 inch). Phoenix typically picks up a quarter of its average yearly precipitation in the months of July and August combined."

Adding to Tuesday's weather excitement, parts of Arizona and Nevada were submerged by heavy rain.

In the Midwest, severe thunderstorm watches were in effect for parts of Michigan, Indiana and Ohio.